Mechanical Devices in the Home

CHAPTER XXXIX

Gas Plants

278. Gasoline-Gas Plants. Gasoline-gas plants are devices for generating gas from gasoline. The gas is a mixture of air and gasoline vapor. It is made by air being forced thru gasoline. There are small plants which can be installed in private homes (Fig. 155). Gasoline vaporizes at ordinary temperature. The vapor or gas produced can be used for heating, lighting and running gas engines.

One gallon of gasoline, when entirely vaporized, produces about thirty-two cubic feet of gas. Its heating power depends upon the character of the gasoline utilized and the temperature at which it is kept during vaporization.

The plant is a device for forcing air thru the gasoline to make it vaporize as fast as wanted. Combined with the carburetor is a storage tank for the gas. A weight, or water motor, furnishes the power most commonly used in forcing the air thru the gasoline and forms a part of the plant. Air cannot flow thru the gasoline when the storage tank is full of gas so that the power is only in operation when the gas is being used or the tank is not quite full.

279. Acetylene-Gas Plant. Acetylene is often used in rural homes when gas or electricity are not available. The operation of the plant often has to be attended to by a member of the family. A capable woman can do this, but she must be careful and must thoroly understand the plant (Fig. 156).

The materials used in making acetylene are calcium carbide and water. Calcium carbide (A, Fig. 156) is made from lime and coke fused together in an electrical furnace. It must be kept stored in a dry place.

The plants for making acetylene are inexpensive enough to be installed in individual homes of moderate means. Calcium carbide for making the gas can be transported without difficulty.

There are two types of machines. In one the water drips on the carbide; in the other, the more common type, the carbide is dropped into the water. As soon as the carbide touches the water, it gives off acetylene gas. The gas is caught in and fills a bell above the water. As it fills the bell, it raises it, and when the bell reaches a certain height, it trips a lever to the door which lets in the carbide and closes it. When the gas is used, the bell goes down and, passing the lever, opens the door to let in a small amount of carbide.

Improvements have been made in the plants and in installing them until there is less danger from explosions than formerly. Great care should be taken in operating them to avoid accidents. Since the gas is highly explosive, fire, lighted lamps and cigars must be kept away from the vicinity of all acetylene plants. Only one person should take the care of the plant, the others should understand how.

280. Directions for Operating Acetylene Plant.

1) Charge by daylight—remove all residuum, and fill with fresh water before adding any carbide.

2) Follow exact directions for the machine used in the order directed.

281. Cautions to Be Observed in Using Acetylene Gas.

1) Do not apply a light to any opening that is not equipped with a regular acetylene burner tip.

2) See that any workman repairing a generator first removes carbide and drains all water out, and disconnects it from piping and removes it to the open air, where he then fills all compartments with water to force out gas before using soldering irons.

3) An open light should never be permitted nearer than ten feet from the generator. The generator should never be nearer than fifteen to twenty feet from furnace or stove. Do not hunt for gas leaks with a flame or light.

4) Do not use any artificial light except electric light when cleaning or repairing generator, or carry a lighted pipe or other fire about it, even when empty.

5) If water in any chamber should freeze, do not attempt to thaw it with anything but hot water.

6) Keep the motor oiled. Oil once in six months.

282. Compressed Gases and Oils. Gases, such as Blau gas, Pintsch gas, and prestolite gas which is compressed acetylene gas, are compressed in strong tanks and sold for use in lighting and light housekeeping. Gasoline and alcohol also are occasionally stored in very strong tanks under enough pressure to make them flow thru very small pipes to the point where they are wanted for use. These are frequently used for lighting isolated public buildings, such as rural schoolhouses.

As the gas or oil is used, the pressure diminishes. There is usually a pump attached to the tank to pump in air in order to keep up the pressure. The pump is similar to a bicycle pump (Fig. 157).

Questions for Part X

PART XI

Measuring Devices

CHAPTER XL

Scales for Weighing

283. Equal-Arm Balances. Scales are devices for determining the weight of objects. Balances—one form of scales—are made of two arms of equal lengths and supplied with discs of metal of a known weight to be placed on one arm of the balance while the material to be weighed is put on the other. When the two arms are in equilibrium, the weight of the material is equal to the weight of the metal. Since the weight of the metal is known, or can be determined, by adding together the weights of the discs used, the weight of the material is known to be the same.

284. Unequal-Arm Balances. Equal-arm balances are not convenient for weighing large objects. For this reason, scales are made with one arm of the balance much longer than the other. The metal discs are then marked with the weight of the material on the short arm which they can balance when placed on the long arm. This is the usual form of counter and household balances. On these scales is also a weight which slides along the arm and is used to determine weights smaller than five or ten pounds. The arm of the balance is, therefore, marked at the point where this weight will balance certain amounts of material, such as half ounces, ounces and pounds.

285. Spring Scales. Spring scales depend on the action of a spring, to which an indicating pointer is attached. When there is no weight on the spring, the place to which the indicator points is marked zero. When these scales are manufactured, a pound weight is placed so that it pulls on the spring and the indicator is pulled down to another place, and this is marked one. Scales are thus marked for the number of pounds they are to weigh. The spaces between the pounds marked are divided into equal divisions, such as sixteenths which indicates ounces. These scales cannot be relied on for accuracy, for springs stretch or become weaker as they are used. Avoirdupois is the weight in common use for marketing, while many tables for calculating dietaries are in the metric system.

The housewife can have her balances corrected for weighing by the city or county sealer of weights and measures so that she can ascertain whether or not her food purchases are correctly weighed.

TABLE OF WEIGHTS

CHAPTER XLI

Devices for Measuring Volume

286. Graduate and Measuring Cup. Graduate holding up to four fluid ounces is helpful to use to check up liquids bought in bottles. The standard measuring cup referred to in modern cook books holds half a pint of liquid. It also holds about sixteen level tablespoonfuls of dry material such as sugar. The divisions on glass cups are less likely to be accurate than on metal ones, as the bottom may be thick or thin unless carefully made. In selecting a cup, see that the bottom section is equal to the other sections.

1 cup = 2 gills = 1/2 pint = 16 tablespoons = 48 teaspoons = 8 fluid ounces.

1 cup is also 1/4 of a quart and about 4/17 of a liter.

287. Tablespoons. Tablespoons vary in size. The size chosen for measuring is the one in most common use and holds about three level teaspoonfuls of material like sugar or flour.

1 tablespoon = 4 drams of liquid = 3 teaspoons.

4 tablespoons = 1/4 cup = 2 fluid ounces.

288. Teaspoons. Teaspoons vary in size, but the spoon in common use is the one understood as the measure in cookery. It holds about one and one-third fluid drams.

289. Standard Measuring Spoons. Standard measuring spoons in sets can be purchased at a very moderate price. They are particularly valuable for checking the capacity of the spoons more commonly used.

290. Liquid and Cooking Measures.

1 teaspoonful = 1-1/3 fluid drams
3 teaspoonfuls = 1 tablespoonful= 4 drams
2 tablespoonfuls = 1 fluid ounce
1/2 cup = 1 gill
2 gills = 1 cupful = 8 fluid ounces
16 tablespoonfuls = 1 cupful
2 cupfuls = 1 pint
2 pints = 1 quart = 4 cupfuls
4 quarts = 1 gallon
4.23 cupfuls = 1 liter
1000 cubic centimeters = 1 liter
1.06 liquid quarts = liter
31-1/2 gallons = 1 barrel
1 milliliter = one-thousandth (.001) liter
1 centiliter = one-hundredth (.01) liter
1 deciliter = one-tenth (.1) liter
Liter = 1 liter
1 dekaliter = ten (10) liters
1 hectoliter = one hundred (100) liters
1 kiloliter = 1 thousand (1000) liters

291. Dry Measures. It is wise for a housewife to have a set of dry measures, consisting of a pint, quart, gallon, peck and half-bushel measure. A quart or gallon liquid measure is not equal to the dry one. It holds less. The diameter of dry measures should be as follows:

DIAMETERS OF DRY MEASURES

*These diameters allow for proper heaping.

DRY MEASURE*

2 pints = 1 quart
8 quarts = 1 peck
4 pecks = 1 bushel
1 sack of flour = 24-1/2, 49 or 98 pounds
4 49-pound sacks of flour = 1 barrel
1 barrel of flour = usually 196 pounds
60 pounds of potatoes = usually 1 bushel

*State laws differ somewhat regarding the number of pounds
in a bushel of various fruits and vegetables.

292. Cubic, Square and Linear Measure.

CUBIC MEASURE

1728 cubic inches = 1 cubic foot

27 cubic feet = 1 cubic yard

128 cubic feet = 1 cord

SQUARE MEASURE

144 square inches = 1 square foot
9 square feet = 1 square yard
30-1/4 square yards = 1 square rod
160 square rods = 1 acre
640 acres = 1 square mile

LINEAR MEASURE

12 inches = 1 foot

3 feet = 1 yard

5280 feet = 1 mile
39.27 inches = 1 meter

METRIC MEASURES

Millimeter = one-thousandth (.001) meter
Centimeter = one-hundredth (.01) meter
Decimeter = one-tenth (.1) meter
Unitemeter = 1 meter
Dekameter = ten (10) meters
Hectometer = one hundred (100) meters
Kilometer = 1 thousand (1000) meters

CHAPTER XLII

Gas, Water, and Electric Meters

293. Different Kinds of Meters. The housewife has need to be familiar with three kinds of meters—water, gas and electric. These are devices for measuring water, gas or electric current.

294. Construction of a Gas Meter. The interior of one type of gas meter (Fig. 158) is somewhat like a water wheel—the pressure of the gas pushes the wheel around. Every time a compartment full of gas passes a certain point, the gas flows out and the flange on the wheel trips a lever which moves the hand of the dial ahead, thus counting the emptying of the compartment. The gas in the compartment back of this then moves to this place. The emptied compartment is filled with more gas as it passes the inlet.

295. Reading the Gas Meter. A gas meter is a device for measuring the number of cubic feet of gas which flows thru a pipe. Small dials with the numbers from one to ten and a hand for an indicator show the number of single feet, tens of feet, and thousands of feet, which have passed thru the meter. The reading on any date is the total amount of gas which has passed thru. To tell how much has passed thru the meter during any period of time, take the reading of the meter on the first date, as indicated in Fig. 158, and then take the reading on the later date and subtract reading one from reading two—the resulting figure is the amount of gas passing thru the meter between these two dates. When buying gas, always keep the readings of meters at the time when the gas man takes them. Gas meters often register more or less gas than is actually consumed. Gas companies are allowed a variation or tolerance of one per cent fast or slow, to two per cent fast or slow. Gas is paid for at a stated rate per thousand feet in most places.

296. Water Meters. The water meter (Fig. 159) is a device for measuring the number of gallons or cubic feet of water which pass thru a pipe. The reading of the meter indicates the total amount of water which has passed thru the pipe since the meter was installed. Water is paid for, unless purchased at a flat rate, at so many cents a thousand gallons or thousand cubic feet. One cubic foot is called in commercial transactions 7-1/2 gallons.

297. Prepayment Meters. Prepayment meters are devices which will permit a certain amount of gas or water, as the case may be, to pass thru a pipe, and after this amount is used up, the pipe is automatically closed so that no more flows until more money is put into the meter. The weight of the coin works the valve.

298. The Electric Meter. Electricity is usually purchased by the kilowatt hour, and measured by the watt-hour meter (Fig. 160). This measures the current passing thru it, and the number of kilowatt-hours is shown by the indicators on the little dials. Start from left and read the number on the dial, such as in the illustration, 3 hundreds 4 tens 9 units, making 349 kilowatt-hours; the total kilowatt-hours used since the meter was installed. To find the number used between two dates, take the reading of the meter on the first date and subtract it from the reading on the second date. The difference is the amount used during the period. Good business women keep records of the readings of their meters. Care must be taken to read the meter correctly. The hand next higher than the one below may read too high. The higher hand may, if out of alignment, pass the figure when the lower hand approaches the ninth point in its dial, this causing the person to read the figures one, ten, hundred or thousand units too much. (Fig. 160-a.)

CHAPTER XLIII

Thermometers and Thermostats

299. Mercury Thermometers. There are two kinds of thermometers in use—the Fahrenheit and the Centigrade. Since the thermometer is used now in cooking, the housewife often has to meet the problem of translating temperatures from one to the other.

The centigrade thermometer is marked on the assumption that the temperatures of boiling water and freezing water are constantly the same. The boiling point is marked 100, and the freezing point 0. The space in between is marked into even divisions and numbered 1 to 99.

The Fahrenheit thermometer was made on the assumption that a mixture of ice and salt was the coldest temperature that could be reached, so this temperature of a certain proportion of ice and salt was marked zero.

The hundred point was given to what was supposed to be the normal body temperature. The intervening spaces were marked into equal divisions, and these divisions were carried below 0 degree and above 100 degrees. The boiling temperature of water came at 212 degrees Fahrenheit, and the freezing point at 32 degrees. This makes 180 degrees difference between thawing and freezing and boiling. So 100 degrees Centigrade equal 180 degrees Fahrenheit. Therefore, 1 degree Centigrade equals 9/5 degrees Fahrenheit, and 1 degree Fahrenheit equals 5/9 degree Centigrade.

For example, if 40 degrees Centigrade is to be translated into Fahrenheit degrees, first multiply 40 by 9 = 360, then divide by 5 = 72, and add 32, because 0 degree Centigrade is the same as 32 degrees Fahrenheit, and the result is 104 degrees Fahrenheit equal 40 degrees Centigrade. If 41 degrees Fahrenheit is to be translated into Centigrade degrees, first subtract 32 from 41 = 9, then multiply by 5 = 45, and divide by 9, and the result is 5 degrees Centigrade = 41 degrees Fahrenheit. Fig. 161 is a diagram showing relative readings of Fahrenheit and Centigrade thermometers.

300. Oven Thermometer. Some oven thermometers depend on the expansion of metal to indicate the temperature. A hand on the clock-like face of these indicators shows the degree of heat. Few of these give the actual temperature, but they do indicate a slow, a moderate and a hot oven.

301. Maximum Thermometers. A maximum thermometer is one in which the mercury rises to register the maximum amount of heat to which it has been subjected. It stays at this height when the temperature falls, until it is shaken back.

It is sometimes used in ovens to ascertain the temperature they have reached before the oven door is opened.

TABLE OF TEMPERATURES USEFUL TO HOUSEKEEPERS

302. Thermostats. Thermostats are devices which open or close valves or dampers in order to keep rooms, boilers, ovens, incubators, etc., at an even temperature. All metals expand on being heated, and contract on being cooled. Some expand more than others. Two materials which expand at different rates are frequently used in making thermostats. Any certain temperature causes a given piece of metal to expand to a certain size, or to contract on cooling to a different size. Some thermostats are made of a straight rod of metal like copper which expands more than iron when heated. The rod is so placed that when cool it will allow fuel like gas or oil to pass thru a pipe, and when heated, it will expand enough to close the pipe, shutting off the fuel. They are placed so that they close the pipe at the temperature desired for an oven or supply of hot water.

Other thermostats are more complicated, as the expanding metal moves a series of levers. These thermostats are used to regulate dampers on coal and wood furnaces, when they are placed in the rooms to be heated. They are often used on other devices, such as incubators.

Still others control an electric current. When the metal expands, it closes the circuit, causing the electricity to do the work desired. When it contracts, it opens the circuit. Thermostats can be set to do work at different temperatures.

These are sometimes attached to clocks which, with a device similar to the alarm, will change the indicator of the thermostat so as to set it from one temperature to another at a stated time for which the clock is set and turn it back at another hour.

CHAPTER XLIV

Hydrometers and Barometers

303. Hydrometer. A hydrometer is used in gaging the density of liquid. This instrument consists of a closed glass tube which is enlarged at the lower end and filled with some heavy material like mercury or shot, to keep it in an upright position when in liquids.

The tube or stem contains a paper on which divisions called degrees are marked. The 0 mark is usually the point reached by the surface of distilled water when the hydrometer is placed in this liquid. The less the density of the liquid, the lower the hydrometer sinks, for it displaces an amount of liquid equal to its own weight. The density of the liquid then can be determined by observing the mark to which it sinks. Specific-gravity hydrometers used in the household show the ratio of the weight of a given volume of liquid to the weight of the same volume of water at a definite temperature. Arbitrary scale hydrometers are used to indicate the concentration or strength of syrup, brines or milk. These are defined as lactometers and Baume hydrometers. A brine hydrometer is called a saltometer, and a syrup gage a sacchrometer. A jellometer, especially for making jelly, is sometimes used instead of a sacchrometer. The scale on this tells how much sugar to use in proportion to the amount of solids in the fruit juice without having to refer to a table. Some hydrometers are constant-volume hydrometers, and on these weights are placed always, to sink the hydrometer to the same depth in the liquid.

TABLES FOR BRIX AND BALLING HYDROMETERS WHEN USED AT 20° C.*

When the reading for the fruit juice is determined the table shows how much sugar is used for juice of that specific gravity.

TABLE SHOWING AMOUNT OF SUGAR PER GALLON

In the second table the readings show the specific gravity of the syrup, and from that may be ascertained the proportion of sugar to a gallon of water in it.

A 250 cc. cylinder, or other tall vessel deep enough to float the sacchrometer, is suitable for making the measurements. Be sure to have the eye on the level of the liquid when making the readings. If no sugar is in the water, the reading on the hydrometer will be near zero. If there is sugar in the proportion of seven ounces to a gallon of water, the reading will be at the line marked 5.

SYRUPS FOR CANNING

304. Hygroscopes. Hygroscopes are devices for measuring humidity. Forty-five to sixty per cent humidity is desirable in a house. This means forty-five to sixty per cent as much water as the air is capable of taking up at room temperature. Cold air is usually dryer than warmer air because cold air cannot take up as much humidity as warm air. This is analogous to the fact that warm water will dissolve more of some salts or of sugar than cold water.

305. Barometers. Barometers (Fig. 162) are devices which show changes in pressure and currents of air. Changes in the barometer usually indicate changes in the weather, and thus they are of interest to all persons. A decided fall in the mercury of a barometer usually precedes foul weather, while a rise indicates the approach of fair weather. When the pressure is low in any locality, air begins to rush toward that point as it would to fill a vacuum. So a fall in the barometer precedes the coming of a high wind or a rainstorm. A rise in the barometer precedes a calm, and since most rain is accompanied with wind, the calm is a time of fair weather.